Compare editing view shows [master language][master language]

Description

This problem occurs sometimes. Here is one scenario.

Precondition: Enable some languages: English, Svenska, Francaise, Espanol.

Steps to reproduce

1. Create a page on English: P1.
2. Translate the page to Svenksa.
3. Switch to the Francaise language.
4. Delete all Svenska branch versions.
5. Create> Start with a new blank on Espanol branch.
6. Open Compare view.

Expected:
Compare view between the English and Espanol display.

Actual:
Compare view shows English and English.